newlib: Enable building libstdc++ for newlib based toolchains
Some baremetal applications might require support from libstdc++
On newlib based toolchains, libstdc++ can be built as a static
library that applications can then link against it.
Pass libsdtc++-(static)dev to LIBC_DEPENDENCIES allowing the
library to be present for cross compilation as well as on
sdk builds.
Signed-off-by: Alejandro Enedino Hernandez Samaniego <alejandro@enedino.org> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
